I MUST have commented on that X and the mat behind it before, but who knows when or where, so here we go. The X is tape of the ground to designate where to stand for transformation zapping, an on the wall is a cushioned mat just in case someone falls back or the TF zappery misses.

Granted, Tedd hasn't actually tested whether the TF gun would leave a mark on a wall, but she doesn't want to find out, either.

The logic of the placement was the least chance to hit anyone or anything other than the intended target by accident without taking up a lot of space in the basement, though there is an argument to having the "X" on its own cushioned mat in the middle of the floor so any falling over would be on said mat.